The invention relates to a tape recorder, and proceeds from a tape recorder in accordance with the preamble of claim 1. A tape recorder is to be understood below as any device in which signals, data or information in analog and/or digital form are recorded on a magnetic tape and/or read from the latter. These devices can have yet further functions independently thereof, for example they can be combined with an electronic camera.
The publication xe2x80x9cTowards the Multitrack Digital Video Tape Recorderxe2x80x9d by Francois Maurice in xe2x80x9cThe Magnetic Society of Japanxe2x80x9d 1991, Volume 15, Pages 389 to 394 discloses a tape recorder in which a multiplicity of data and/or signal tracks are recorded on a magnetic tape using the method of longitudinal track recording. In the device disclosed in said printed publication, the data tracks are written simultaneously by means of a matrix head. In an exemplary embodiment of said device, up to 80 parallel tracks with a width of 7 xcexcm are written without grass, that is to say without an interspace between the individual tracks. Owing to the large number of data tracks, it is possible to reduce the tape speed by a corresponding factor for a prescribed data rate to be recorded. On the one hand, a very high recording density is thereby achieved on the magnetic tape, while on the other hand, it is very difficult in practice to integrate in a reading unit many inductive heads situated close to one another. Consequently, to read the data use is made of a magneto-optic scanning device whose essential element is a magneto-optic transducer which utilizes the magneto-optic Kerr effect. The magneto-optic transducer is arranged transverse to the longitudinal extent of the magnetic tape and has a length which permits several data tracks to be read out simultaneously.
As in the case of all tape recorders, it is also necessary in this case for measures to be taken so that the user is given a display of the state of the tape. It is conventional for this purpose to record parallel to the data tracks a control track which is read by an additional inductive control head. In order to avoid the outlay on the additional control head, it is also known to store the information for orientation in the longitudinal direction of the magnetic tape in outer tracks of the track packet, and to read it out likewise via the magneto-optic transducer. This solution requires less outlay and, moreover, not only permits orientation in the longitudinal direction of the tape, but also renders it possible to utilize the edge tracks for positioning the write and/or read head. Common to both solutions, however, is that the magnetic tape must be transported at least a short distance in the longitudinal direction in order to determine the current position of the magnetic tape. Although this operation proceeds automatically, it requires time and consumes energy, and this is a disadvantage, particularly in the case of battery-operated devices.
Starting from this point, it is the object of the invention to create a tape recorder in which the current tape position of a newly inserted cassette is displayed without the need to transport the magnetic tape in the longitudinal direction.
This object is achieved by means of a tape recorder which is characterized in that the reading device is suitable for detecting additional information stored on the magnetic tape in the vertical direction.
This tape recorder renders it possible for information to be read from the magnetic tape without the need for transportation in the longitudinal direction for this purpose.
The reading unit advantageously has a magneto-optic transducer which is constructed so that it can simultaneously sense a number of parallel data tracks. The magneto-optic transducer can expediently have a length such that in specific positions on the magnetic tape all the additional information stored thereon in the vertical direction can be sensed. It is particularly expedient if the additional information contains the information on the state of the tape.
In an expedient development of the invention, the tape recorder has a drive device for the magnetic tape, which is controlled by a control unit. The control unit receives from the reading device a control signal which indicates when the magneto-optic transducer senses the additional information. In a development of the invention, said control signal can be used so that the drive device of the magnetic tape stops only in the positions in which the reading device senses the additional information. It is ensured in this way that a magnetic tape can be removed only in a position in which it is possible that when the tape is reinserted the additional information can be read by the magneto-optic transducer without the need to transport the tape in the longitudinal direction. It is advantageous for the spools in a cassette to be locked by latching means upon removal from the tape recorder. When the cassette is inserted into the tape recorder, actuating means can disengage the latching means again.
The invention further relates to a method for writing and/or reading signals or data onto or from a magnetic tape. The invention proceeds from a method in which data are recorded on a magnetic tape in data tracks arranged in parallel, and in which, moreover, additional information are recorded which specify the tape position.
Such methods are known from the prior art, but they all without exception require the magnetic tape to be transported at least a short distance in the longitudinal direction.
Starting from this, it is a further object of the invention to specify a method in which additional information is stored on the magnetic tape in such a way that the information on the state of the tape can be read off without the need to transport the magnetic tape.
This object is achieved by means of a method which is characterized in that additional information is stored perpendicular to the data tracks recorded in longitudinal tracks.
In accordance with an exemplary embodiment of the method according to the invention, portions of the additional information can be recorded inside different data tracks, the portions of the additional information which are contained in different data tracks being strongly correlated in the direction perpendicular to the data tracks.
The data are advantageously recorded as digital signals in the data tracks, there being sent in advance of the principal data pilot signals which serve to tune the reading unit before the principal data intended for further processing are read out. In this case, it is possible for the additional information to be stored in the spatial region on the magnetic tape which is occupied by the pilot signals in the individual data tracks. This has the advantage of excluding any type of interference between the principal data and the additional information.
Finally, the invention relates to a magnetic tape in which a multiplicity of parallel data tracks are recorded using the method of longitudinal track recording.
Such magnetic tapes are known in the prior art. However, they have the disadvantages described at the beginning in connection with displaying the state of the tape.
It is the object of the invention starting herefrom to create a magnetic tape in which the information on the state of the tape can be read off without the need to move the magnetic tape in the longitudinal direction.
This object is achieved by means of a magnetic tape which is characterized in that the additional information is recorded in the direction perpendicular to the data tracks.
In an expedient embodiment of the magnetic tape, the additional information can be strongly correlated perpendicular to the direction of the parallel data tracks.